U.S. patent number 4,341,226 [Application Number 06/189,531] was granted by the patent office on 1982-07-27 for temporary lead with insertion tool.
This patent grant is currently assigned to Medtronic, Inc.. Invention is credited to Peter Peters.
United States Patent |
4,341,226 |
Peters |
July 27, 1982 |
Temporary lead with insertion tool
Abstract
A temporary lead for pacing or monitoring purposes with
insertion tool. The temporary lead is thin and lightweight having
an electrical connector at a proximal end and an electrode at a
distal end. A length of surgical thread is permanently attached to
the electrode. A helix is molded into the surgical thread at a
short distance from the electrode. A curved needle is permanently
attached to the surgical thread. The curved needle is inserted into
a first location of the tissue manually or using the disclosed tool
which provides insertion at a fixed depth. The curved needle exits
the tissue at a second location. The curved needle and surgical
thread are pulled from the second location thus bringing the
electrode into sufficient contact with the tissue. The helix is
elongated under the stress of tension supplied to pull the
electrode into position. The excess surgical thread is cut at the
second location, removing the tension. The helix tends to return to
its initial shape, thereby holding the electrode in position until
removal. A straight cutting needle, crimped to the proximal end of
the electrical conductor, leaves the body percutaneously prior to
closing the wound. Upon applying longitudinal force at the proximal
end, the helix is again elongated and the lead is removed. The
insertion tool moves the curved needle in a fixed arc relative a
surface held against the tissue surface. The fixed arc causes a
fixed insertion depth as the curved needle travels from the first
location to the second location.
Inventors: |
Peters; Peter (Brunssum,
NL) |
Assignee: |
Medtronic, Inc. (Minneapolis,
MN)
|
Family
ID: |
22697734 |
Appl.
No.: |
06/189,531 |
Filed: |
September 22, 1980 |
Current U.S.
Class: |
607/132 |
Current CPC
Class: |
A61N
1/0587 (20130101) |
Current International
Class: |
A61N
1/05 (20060101); A61N 001/04 () |
Field of
Search: |
;128/419P,784,785 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Kamm; William E.
Attorney, Agent or Firm: Rooney; John L. Breimayer; Joseph
F. Forest; Carl A.
Claims
What is claimed is:
1. A lead for establishing electrical contact between body tissue
and a medical device comprising:
a length of conductor having a proximal end and a distal end;
a sheath attached to the surface of said length of conductor;
connector means fixedly attached to said proximal end of said
length of conductor for electrically coupling said lead to said
medical device;
an electrode fixedly attached to said distal end of said length of
conductors;
a length of surgical thread having a proximal end and a distal end
wherein said proximal end of said length of surgical thread is
fixedly attached to said electrode;
a needle fixedly attached to said distal end of said length of
surgical thread; and
means fixedly attached to said length of surgical thread for
frictionally resisting the movement of said surgical thread
relative to said body tissue.
2. A lead according to claim 1 wherein said frictionally resisting
means is fixedly attached to said length of surgical thread at a
distance from said proximal end of said length of surgical
thread.
3. A lead according to claim 2 wherein said frictionally resisting
means further comprises portion of said length of surgical thread
having the general shape of a helix.
4. A lead according to claim 1, 2 or 3 wherein said needle is a
curved surgical needle.
5. A temporary pacing lead for providing electrical connection
between a pulse generator and epicardial tissue comprising:
a length of flexible conductor having a proximal end and a distal
end;
insulating sleeve of material substantially inert-to-body fluids
fixedly attached to the outer surface of said length of flexible
conductor;
a connector means fixedly attached to said proximal end of said
length of flexible conductor for electronically coupling said
temporary pacing lead to said pulse generator;
an electrode fixedly attached to said distal end of said length of
flexible conductor;
a length of surgical thread having a proximal end fixedly attached
to said electrode, having a helix molded into said length of
surgical thread at a short distance from said proximal end of said
length of surgical thread, and having a distal end; and
a curved needle fixedly attached to said distal end of said length
of surgical thread.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a surgical electrode
lead and more specifically relates to a lead for temporary
application.
2. Description of the Prior Art
The use of temporary leads for pacing and monitoring purposes is
quite common. Specially designed leads are used for such temporary
applications which are much lighter and less durable than permanent
leads since extended flex life is not required. It is still
critical, however, that electrodes be properly affixed to tissue to
permit the required transfer of electrical energy. This electrical
contact must be established in a manner which permits convenient
and safe removal of the lead with minimal permanent scarring and
other effects. Furthermore, for expicardial applications, most
permanent leads are more costly than is felt justified for
temporary use.
Ackerman teaches construction of temporary leads for curing cardiac
arrest in U.S. Pat. Nos. 3,485,247 and 3,516,412. The former
reference uses a hook-shaped tip for affixing the lead whereas the
latter uses resiliency of shape. Neither of these techniques is
suitable for most applications, however, as both leads are intended
to be percutaneously inserted and actually puncture the myocardium.
Because of the permanent effects of this technique, it is not
useful under routine circumstances.
The primary method of affixing temporary epicardial leads is with
sutures. Typically, this technique provides the greatest
reliability with minimal permanent damage. Sutures were used in the
earliest pacing applications for affixing all leads. U.S. Pat. No.
3,244,174, issued to Wesbey, et al., teaches a lead whose
electrodes are affixed using a suture pad.
U.S. Pat. No. 3,474,791, issued to Benton, teaches a lead having
insulation removed at points which permit electrical contact. The
lead may have a curved surgical needle attached directly to the
distal end of the conductor for sticking the lead directly into the
myocardium. Additional sutures are used to further attach the lead
to the epicardium.
These earlier suturing techniques for affixing the electrode to the
myocardium lend themselves primarily to permanent implantation,
since removal of the lead is difficult.
SUMMARY OF THE INVENTION
The present invention is for temporary epicardial stimulation or
monitoring. The lead is less expensive than permanent leads, being
intended for short-term use only. A single suture affixes the
electrode to the epicardium. A length of surgical thread and a
curved needle are permanently affixed to the electrode at the
distal end of the lead. A helix is molded into the surgical thread
a short distance from the electrode.
The curved needle enters and exits the epicardium and the surgical
thread is manually pulled until the electrode actually enters the
tissue. The helix within the surgical thread is spaced a distance
from the electrode ensuring that it is located within the
myocardium. The pulling tension on the surgical thread elongates
the helix. With tension on the surgical thread, the excess surgical
thread is cut at the point of exiting the epicardium. Cutting the
surgical thread releases the tension on the helix tending to allow
it to return to its original shape. This tendency of the helix
holds the electrode in place.
To facilitate proper depth of the stitch, an insertion tool is
provided which rotates the curved needle through a fixed arc at a
fixed distance relative the epicardial surface. The insertion tool
has a shank with a handle at one end and a rotating disc at the
other. A pushbutton on the handle causes the disc to rotate a
partial turn in one direction. A spring causes the disc to return
to its original position. The curved needle is inserted into a slot
near the circumference of the disc. The disc end of the insertion
tool is held against the epicardium. Pressing of the pushbutton
causes insertion of the curved needle to a fixed depth.
After the temporary lead is no longer needed, the lead is removed
by pulling on the proximal end. The tension thus created tends to
elongate the helix thereby easing removal.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a view of the entire temporary lead.
FIG. 2 is a side sectional view of the electrode with surgical
thread and helix attached.
FIG. 3 shows the curved needle as inserted into the myocardium at
proper depth.
FIG. 4 shows elongation of the helix as the electrode is pulled
into position.
FIG. 5 shows cutting off excess surgical thread.
FIG. 6 is a sectional view of the myocardial tissue with tension
applied to surgical thread.
FIG. 7 is a sectional view of the myocardial tissue with tension
removed.
FIG. 8 shows the insertion tool.
FIG. 9 schematically shows the operation of the insertion tool.
FIG. 10 shows insertion of the curved needle using the insertion
tool.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention is disclosed as embodied in a temporary
pacing lead and associated insertion tool. Experiments have
indicated that manual insertion of the curved needle is most
satisfactory when using the lead for ventricular pacing. The
insertion tool is intended for use in the atrial region as the
myocardial tissue there is much thinner. However, those of ordinary
skill in the art will be readily able to utilize the present
invention in other applications and with different dimensions.
FIG. 1 shows the temporary pacing lead. The proximal end contains a
metallic, electrically conductive needle 12 which is used as a
connector pin to couple the lead to a pulse generator. Needle 12 is
attached to the flexible conductor 14 which runs the length of the
temporary pacing lead and is attached to electrode 16. Sheath 10 is
of a material substantially inert to bodily fluids such as
polyethelene. Sheath 10 also electrically insulates conductor 14. A
length of surgical thread 18 is permanently attached to electrode
16. Surgical thread 18 has an outside diameter of about 0.35 mm and
is a commonly available type such as polypropylene. Helix 20 is
molded into the surgical thread by applying hot air to the coiled
surgical thread. Curved needle 22 is a standard surgical -3/8
circle needle of 12.0 mm radius. The surgical thread is attached to
the curved needle by crimp 22b. Needle point 22a is hand honed.
FIG. 2 is a sectional view of electrode 16. The total length of
electrode 16 is about 3 mm. The outside diameter of Sheath 10 is
approximately 0.7 mm. Sheath 10 extends to the proximal end of
electrode 16. Conductor 14 extends distal relative to Sheath 10 and
into electrode 16 as shown. Electrode 16 is crimped to securely
connect to conductor 14 at indentation 16b. The proximal end of
surgical thread 18 is enlarged to produce fastener 24. This may be
accomplished by heating the proximal end of surgical thread 18 and
applying a force in the distal direction, thus flatening the
end.
Fastener 24 is inserted into chamber 16c which lies within
electrode 16 between the distal end of conductor 14 and the distal
end of electrode 16. The distal end of electrode 16 is swaged
producing the conical frustrum 16a, which securely holds fastener
24. Conical frustrum 16a also helps ease insertion of electrode 16
into epicardial tissue.
Between conical frustrum 16a and helix 20 is a length of surgical
thread 18a being about 1.0 mm. Helix 20 is about 9-11 turns having
an outside diameter of approximately 1.0 mm.
FIG. 3 shows proper insertion of curved needle 22. This may be
accomplished manually or through the use of the insertion tool
described below. Myocardium 26 is entered at first location 30 and
exited at second location 32 by curved needle 22 being moved in the
direction shown.
FIG. 4 shows the manner in which electrode 16 is properly
positioned. Surgical thread 18 is manually pulled from second
location 32 until electrode 16 to which it is attached is pulled
into the orifice at location 30. Notice that electrode 16 is
located completely within myocardial tissue. Because of the stress
on helix 20 caused by pulling surgical thread 18 in the direction
shown and the friction between electrode 16 and the myocardial
tissue, helix 20 becomes temporarily elongated as shown. FIG. 6
shows an enlarged sectional view of myocardial tissue 26 with
electrode 16 properly positioned. Notice that a portion of
elongated helix 20 extends from the orifice at second location
32.
FIG. 5 shows removal of the excess surgical thread. While tension
is continuously supplied to surgical thread 18 maintaining helix 20
in its elongated state, surgical thread 18 is severed by cutting
instrument 28 near second location 32. FIG. 7 is an enlarged
sectional view of myocardial tissue 26 following severing of the
excess surgical thread. Notice that whereas helix 20 does not
return to its initial shape, its longitudinal distance is somewhat
reduced causing the tension with the surrounding myocardial tissue
which continues to hold electrode 16 in place. Also notice that
helix 20 was severed at point 20a. Severing the surgical thread at
helix 20 ensures that point 20a will retreat from second location
32 into the myocardial tissue which permits immediate healing of
second location 32.
To remove the temporary pacing lead, tension is applied by pulling
the proximal end of the temporary pacing lead. The tension tends to
elongate helix 20 easing removal. Notice that healing need occur
only at a single orifice (i.e., at first location 30) upon removal
as the orifice at second location 32 begins healing
immediately.
FIG. 8 shows insertion tool 50. As explained above, the use of
insertion tool 50 is optional but has proven useful for atrial
pacing. Because the thickness of the myocardium in the atrial
region is substantially less than in the ventricular region,
obtaining of proper depth without piercing the endocardium is more
difficult. Insertion tool 50 ensures a constant insertion
depth.
Insertion tool 50 has a handle 52 with a pushbutton 54 which is
most conveniently pressed by a thumb. Shank 56 contains slot 70 in
which cable 66 is stretched. Cable 66 is attached to pushbutton 54
in such a fashion as to be pulled toward handle 52 as pushbutton 54
is depressed. Tool head 58 contains disc 62 which is rotatably
attached to tool head 58 by axle 74. Cable 66 is attached to disc
62 in such fashion that disc 62 tends to rotate in a clockwise
direction as cable 66 moves toward handle 52. Surface 60 is placed
against the epicardium during insertion. Insertion depth is
determined by the distance between surface 60 and axle 74. Curved
needle 22 (not shown) is inserted into slot 64 in preparation for
insertion.
FIG. 9 is a schematic diagram of the operation of insertion tool
50. As can be seen, pushbutton 54 is pivotally mounted to handle 52
by axle 72. Cable 66 is attached to pushbutton 54 at connection
point 84. Fixed member 74 is attached to handle 52 to ensure that
depressing pushbutton 54 in the direction shown causes cable 66 to
be drawn toward pushbutton 54. Channel 68 in pushbutton 54 prevents
cable 66 from binding against fixed member 74.
As pushbutton 54 is depressed and cable 66 is drawn toward
pushbutton 54, pulley 76 is caused to rotate in a clockwise
direction freeing additional cable 78. Rotation of pulley 76 causes
rotation of axle 74 to which it is attached. Disc 62 is shown in
cutaway fashion. As axle 74 rotates, disc 62 rotates as shown.
Curved needle 22, having been inserted into slot 64, is also
rotated to enter the epicardium. Spring 80 tending to cause
counterclockwise rotation of axle 74 causes disc 62 to return to
its initial position upon release of pushbutton 54. Surface 60 is
shown. Distance 82 is the distance between the arc traced by needle
point 22a and surface 60. Distance 82 is the constant stitch depth
produced by insertion tool 50. This distance is, of course,
modifiable by changing the distance between surface 60 and axle 74
or the radius of curved needle 22 and disc 62. At present, 1-2 mm
is thought appropriate.
FIG. 10 shows insertion of needle 22 into myocardial tissue 26
using insertion tool 50. Notice that surface 60 is positioned flush
with the epicardial surface. As needle 22 is rotated in the
direction shown proper insertion is accomplished as seen in FIG.
3.
* * * * *